Can you really say you are the same person you used to be? If you ran into your past self, would they see you as a changed person? It's impossible to stay the same. Change is inevitable. This is a story that may or may not have happened. Hypothesis drift in space-time. Abstract theories wander the dimensions. But stories... they travel from heart to heart. Some things are better left the way they are. Like the relationship between environmentalists and hyperdiverse societies. Condemning or excluding people with specific traits only ends up harming society as a whole. Thus, societies have accepted the idea of a cordial existence. Today you, tomorrow me. On the one hand, extreme environmentalism has led to the creation of meaningless artificial green cities, whereas advocates for hyper-diversity have led to the creation of societies that readily accept anything in the name of individuality. Fixing these problems would be a task, so it's best to eliminate them altogether. But does that qualify as a solution to the problem? Renko Usami was doubtful about that.

Renko Usami is a member of the occult circle known as the Secret Sealing Club. She goes by the name Renko. I'm the only one who knows what Renko Usami is really like... she is actually a very lovely girl. (M.H.) Maribel Hearn is a member of the occult circle known as the Secret Sealing Club. She goes by the name Merry. I know something about Merry that no one else does. She's like the human equivalent of the golden ratio. She looks beautiful no matter what she does. (R.U.)

Renko has known for a long time that Merry has mysterious powers. Merry can see the cracks in boundaries, the so-called "gaps." She can also enter dreams. Her abilities have slowly grown over time, and she can now peek into various other worlds or even travel to distant places like Torifune. To Renko, these are no different from dreams or visions that she experiences with Merry. But to Merry, they are as good as reality. She once got injured in Torifune, and it turned into a real wound. It was so bad that she had to get quarantined for treatment. Merry didn't have any relatives in Japan, so Renko went to pick her up from the sanatorium in Shinshu. They decided to do a little sightseeing before heading back. On their way, Renko started pondering. Doctors had diagnosed Merry with an unknown viral disease. But that's basically just their way of saying she's suffering from a mental illness that doesn't fit society's definition of normal. Either way, their conclusions were tailored to fit our modern society's definitions. They claimed to understand and accept what was happening to her, but they were simply dismissing and rejecting the reality of it. Maybe that's the limitation of relative psychology. Although no one knew what had really happened, Renko felt like it was up to her to figure out how exactly Merry's mysterious ability worked.

Izanagi Objects Every barrier that has been detected around the world is treated as a new phenomenon by super-unified physicists. It's not surprising because they wouldn't be able to make any sense of them otherwise. They treat dangerous barriers the same as crumbling cliffs and rivers with strong currents. But aren't barriers much more dangerous than that? Merry's ability allows her to see mysterious worlds when she holds an Izanagi Object. And she can share this vision with Renko by touching her. That is how they saw a different version of Japan. And perhaps that is where the things that super-unified physicists blatantly ignore can be found.

"Let's go, Merry." "OK, Renko." The two began their journey across the country in search of Izanagi Objects. This journey later became the basis of a certain book because it was also an adventure to see more mysterious worlds. The Secret Sealing Club, which until then was mostly fun and games, now had a goal. Things that seem to originate from myths are most likely made of Izanagi Objects. And because Merry and Renko were open to that idea, they opened doors to the secrets of the universe. Perhaps you could call those doors gaps in a barrier, or maybe it would be better to split everything into two categories―barriers and things that transcend them. Renko wondered whether Izanagi Objects could be multidimensional structures that connect to other worlds... by maybe piercing perpendicularly through higher dimensions. But she had no way to prove her hypothesis, so she dropped the idea. She decided to give it some more thought if and when she came across more information. Right now, she wanted to focus on enjoying her time with Merry.